Thermosetting resin composition comprising an aromatic amine

ABSTRACT

The invention relates to an aromatic amine resin comprising a mixture of aromatic amine compounds represented by the following general formula (a): ##STR1## wherein A represents a phenylene, alkyl-substituted phenylene, diphenylene, diphenyl ether or naphthylenyl group, R 1  represents a halogen atom or a hydroxyl C 1-4  alkoxy or C 1-5  alkyl group, l is 1 or 2, m is 0, 1, 2 or 3, n is an integer from 0 to 300 and when m is 2 or 3, the R 1  group may be the same or different and may join to form a 5- or 6-membered alicyclic moiety which may optionally contain one or more side chains, and also relates to processes for producing the same and a thermosetting composition containing the same.

This application is a divisional of application Ser. No. 254,0701, filedOct. 7, 1988 U.S. Pat. No. 4,937,318.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates to novel aromatic amine resins, processes forproducing the same and thermosetting resin compositions containing thearomatic amine resins.

(2) Description of the Related Art

It has been known for many years that aromatic amine resins arecondensation products of aromatic amines and formaldehyde. For example,an aniline-formaldehyde resin represented by the following generalformula (f): ##STR2## has been produced [K. Frey, Herbetica Chemie Acta,18, 481 (1935)].

However, it is difficult to introduce maleimide or isocyanate groupsinto conventional aromatic amine resins such as an aniline-formaldehyderesin represented by the general formula (f). Such amine resins arehence not suitable as raw materials for maleimide resins or isocyanateresins. Conventional aromatic amine resins have therefore been usedwidely as curing agents. Today, increasingly sophisticated applicationand more rigorous expectation in performance and consistency ofperformance require that aromatic amine resins be suitable for use inmatrix resins of heatresistant composite materials,high-temperatureresistant bonding agents and the like. These demands canno longer always be met adequately by conventional aromatic amineresins.

Heat-resistant composite materials, high-temperature-resistant bondingagents, and the like are required to withstand instantaneous impact suchas stress concentration from an external stress. Ideally, the ability ofundergoing an elastic deformation like rubber is an important and highlydesirable property. The elastic deformation property of a resin isevaluated by measuring the elongation at a break of each matrix resin.The greater the elongation of the matrix resin, the greater the overallstrength of a composite material. Thus, the drawbacks of the presence ofa reinforcing material such as glass fibers or carbon fibers requiredfor a composite material can be compensated.

For such matrix resins and the like, long-term storage stability, heatresistance and dimensional stability are also important properties. Suchresins are also required to undergo less deterioration by light oroxygen in the air. This oxidation resistance is primarily attributableto the structure of each resin. In addition to failing to satisfy theabovementioned demands for mechanical strength, conventional aromaticamine resins involve difficulties in overcoming various drawbacks whichare attributed to their structural defects.

The aniline-formaldehyde resin represented by formula (f) above; isconverted into a crosslinked structure when the molar ratio offormaldehyde is increased upon condensation thus increasing the degreeof condensation and improving its mechanical properties and the like.Accordingly, it is only possible to increase the molecular weight ofsuch a resin to about 600 [Noda, et al., Nippon Kogyo Kagaku Zasshi, 55,484-487 (1952)].

The present inventors have already discovered novel aromatic amineresins which have improved upon these drawbacks. A patent applicationcovering such aromatic amine resins was filed on Sept. 17, 1987 in Japan(Japanese Patent Application No. 230987/1987). However, since theseresins are composed of a secondary amine, it is difficult to achieveisocyanation or maleimidation. They are accompanied by further problemssuch that when used as a curing agent, these resins must be employed ina relatively large amount and their curing speeds are relatively slow.

On the other hand, thermosetting resins having an imide structure havealready found wide-spread industrial utility due to their excellentelectrical insulation, heat resistance and dimensional stability ofmoldings.

However, thermosetting resins which are obtained by separatelysubjecting aromatic bismaleimides to heat polymerization have drawbackssuch as being extremely brittle and having poor flexibility. As a methodfor improving such drawbacks, it has been attempted to use athermosetting resin composition composed of an aromatic bismaleimide andan aromatic diamine. For example, a polyaminobismaleimide resin("Kerimid", trade mark; product of Rhone-Poulanc S.A.) composed ofN,N'-4,4'-diphenylmethanebismaleimide and 4,4'-diaminodiphenylmethanehas been used widely in impregnating varnishes, laminated boards,moldings, etc. (Japanese Patent Publication No. 23250/1971).

However, such thermosetting resin compositions do not have sufficientheat resistance and are not satisfactory either in impact resistance orflexibility.

SUMMARY OF THE INVENTION

A first object of this invention is to provide a novel aromatic amineresin which when used as a curing agent, provides a cured resin havingexcellent heat resistance, mechanical strength, dimensional stability,and light and air oxygen stability and which is also useful as a rawmaterial for isocyanate resins, maleimide resins and the like.

A second object of this invention is to provide a novel process for theproduction of the above aromatic amine resin.

A third object of this invention is to provide a process that is moreeconomical, less costly, and produces less side reactions than prior artprocesses.

A fourth object of this invention is to provide a novel thermosettingresin composition having excellent mechanical strength and heatresistance.

The present invention overcomes the problems and disadvantages of theprior art by providing an aromatic amine resin which when used as acuring agent provides a curing resin having superior properties. In oneaspect of this invention, there is thus provided an aromatic amine resinformed of a mixture of aromatic amine compounds represented by thefollowing general formula (a): ##STR3## wherein A represents aphenylene, alkyl-substituted phenylene, diphenylene, diphenyl ether ornaphthylenyl group; R¹ represents a halogen atom or a hydroxyl; C₁₋₄alkoxy or C₁₋₅ alkyl group; l is 1 or 2; m is an integer from 0 to 3;when m is 2 or 3, R¹ may be the same or different and two of R¹ groupsmay join together to form a 5- to 6-membered alicyclic moiety which maycontain one or more side chains; and n represents an integer of from0-300.

In another aspect of this invention, there is also provided a firstprocess for the production of the above aromatic amine resin, whichcomprises reacting in the presence of an acid catalyst an aromatic aminerepresented by the following general formula (b): ##STR4## wherein R¹, land m have the same meanings as defined with respect to formula (a),with an aralkyl alcohol derivative represented by the following generalformula (c):

    R.sup.2 OCH.sub.2 --A--CH.sub.2 OR.sup.2                   (c)

wherein A has the same meaning as defined with respect to formula (a)and R² is a hydrogen atom or an acyl or C₁₋₄ alkyl group.

In a further aspect of this invention, there is also provided a secondprocess for the production of the above aromatic amine resin, whichcomprises reacting the aromatic amine of the formula (b) with abishalogenomethyl derivative represented by the following generalformula (d):

    X--CH.sub.2 --A--CH.sub.2 --X                              (d)

wherein A has the same meaning as defined with respect to formula (a)and X is a halogen atom. The reaction of this process can be conductedeven in the absence of any catalyst.

In a still further aspect of this invention, there is also provided anovel thermosetting resin

composition comprising 100 parts by weight ofN,N'-4,4'-diphenylmethanebismaleimide represented by the followingformula (e): ##STR5## and 5-100 parts by weight of the aromatic amineresin represented by the general formula (a).

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 diagrammatically shows results of an IR analysis of an aromaticamine resin obtained in Example 1.

DETAILED DESCRIPTION OF THE INVENTION

The aromatic amine resins according to this invention can be used in awidevariety of fields, for example, as raw materials for epoxy resins orcuringagents for other epoxy compounds, as raw materials for maleimideresins or curing agents for other maleimide compounds, as raw materialsfor isocyanate resins or curing agents for other isocyanate compounds,as chelate, resins, ion-exchange resins, molding materials, insulatingpaints, bonding agents, rubber modifiers, additives for various resins,deacidification agents, and as raw materials for polyimides, polyamidesand polyamideimides, etc.

Since the aromatic amine resins according to this invention are composedofa primary amine, it is easy to achieve isocyanation, maleimidation orepoxidation.

Further, resins having high performance can be obtained by using thearomatic amine resins of this invention as curing agents for otherresins (for example, isocyanate compounds, epoxy compounds, bismaleimidecompounds, etc.).

When the resins according to this invention are used as curing agentsfor bismaleimide compounds, the resultant cured resins exhibit excellentmechanical strength, dimensional stability, heat resistance and lightand air oxygen stability. Their curing speeds are also high. Forexample, use of any one of the resins according to this invention as acuring agent forbismaleimide derived from methylenedianiline can providea cured resin whose flexural strength, flexural modulus, pyrolysisstarting temperature in air, coefficient of expansion and waterabsorption rate are superior tothose of "Kerimid 1050" (trade name;molding grade; product of Rhone-Poulanc S.A.) obtained by usingmethylene-dianiline as a curing agent. Their glass transitiontemperatures and heat distortion temperatures are substantiallycomparable.

In addition, the resins according to this invention are soluble in lowboiling point solvents (dioxane, methylene chloride, etc.).

A prepreg has heretofore been prepared by dissolving a prepolymer suchas "Kelimide" in a high boiling point aprotic polar solvent(N-methylpyrrolidone or the like) and then impregnating glass cloth orcarbon cloth with the solution. In contrast to such a conventionalmethod,use of any one of the resins according to this invention as aprepolymer facilitates the evaporation and removal of the solvent toprovide an excellent prepreg since the resin can be dissolved in a lowboiling point solvent.

The resins according to this invention are faster in curing speed thanthe resins disclosed previously by the present inventors in JapanesePatent Application No. 230987/1987. Thus, the former resins arepreferred particularly for use as sealing resins for semiconductors.

The first production process according to the present invention willnext be described.

The resins according to this invention can each be produced bysubjecting the aromatic amine compound represented by the generalformula (b) and thearalkyl alcohol derivative represented by the generalformula (c) to a co-condensation reaction. If aniline and the aralkylalcohol derivative are caused to undergo co-condensation in the courseof the reaction, a resin containing a secondary amine such as thathaving a structure of the following formula (g): ##STR6##is formed. Itis however only necessary to convert the secondary amine resin into aprimary amine resin of this invention by a rearrangement reaction. Thisrearrangement reaction can be conducted, for example, by (a) increasingthe amount of the catalyst, (b) by increasing the reaction temperatureor (c) by increasing the reaction time compared to the reactionconditions under which the secondary amine is formed. In particular, itis effective to increase the amount of the catalyst.

As already mentioned above, it has been only possible to increase themolecular weight of the conventionally-known aniline-formaldehyde resintoabout 600. In contrast, the aromatic amine resins according to thisinvention may each be chosen as desired from a low molecular resincomposed principally of the aromatic amine compound of the generalformula(a) in which n is 0, to a high molecular resin composed of thearomatic amine compound principally of the general formula (a) in whichn is about 300. Thus, by the first production process of this invention,aromatic amine resins ranging in a form from a liquid resin at roomtemperature to a high softening point resin in a resinous form can beproduced, dependingupon the intended end use.

Resins according to this invention, ranging from liquid resins to thosehaving a low softening point, can be obtained provided that the molarratio of the aromatic amine compound to the aralkyl alcohol derivativeis increased. The liquid-low softening point resins thus obtained areexcellent in workability upon melt blending, impregnation, coating andthelike and are useful as bonding agents, paints, and additives forurethane and other resins.

High softening point resins according to this invention can be obtainedprovided that the molar ratio of the aralkyl alcohol derivative to thearomatic amine is near a stoichiometric ratio upon their condensation.Thehigh softening point resins obtained are useful as molding materials,ion-exchange resins and laminating resins.

The molecular weight range of the aromatic amine resins obtained asdescribed above in accordance with the first production process of thisinvention range from about 300 to about 60,000. The softening point oftheresins range from a liquid state at room temperature to about 250.C(as ring and ball softening points measured in accordance withJIS-K-2548).

In the first process of the invention, the aromatic amine compoundrepresented by the general formula (b) is preferably employed in anamountof from about 1-15 moles, more preferably from about 1.1-10 molesper mole of the aralkyl alcohol derivative represented by the generalformula (c). The compounds are heated in the presence of an acidcatalyst. Water, alcohol, organic acid and/or the like, which are formedas the reaction proceeds, are trapped outside the system. Volatileswhich remain at trace levels within the system may be purged out withnitrogen if necessary. When it is desired to obtain a relatively lowmolecular resin composed principally of the aromatic amine compound ofthe general formula (a) in which n is 0, it is desirable to increase theabove-mentioned molar ratio.A greater molar ratio however results inmore unreacted amine and thus, more time and labor are required for itsremoval after the reaction. Preferably, the molar ratio of the aromaticamine compound to the aralkyl alcohol is not greater than 10.

Illustrative examples of A in the aralkyl alcohol derivative, which isuseful in the practice of suitable groups for use as substituent A inthe alalkyl alcohol derivative represented by the formula (c), include##STR7##R² is a hydrogen atom or an acyl or alkyl group. When R²represents an acyl or alkyl group containing no more than four carbonatoms, the reaction velocity is high. When the carbon number is 4, andR² is a butyl group or tert-butyl group, the reaction proceeds at a lowreaction velocity. Illustrative examples of aralkyl alcohol derivativesuseful in the practice of this invention includeα,α'-dihydroxy-o-xylene, α,α'-dihydroxy-m-xylene,α,α'-dihydroxy-p-xylene, α,α'-diacetoxy-o-xylene,α,α'-diacetoxy-m-xylene, α,α'-diacetoxy-p-xylene,α,α'-dipropionoxy-p-xylene, α,α'-di-n-butyloxy-p-xylene,α,α'-dimethoxy-o-xylene, α,α'-dimethoxy-m-xylene,α,α'-dimethoxy-p-xylene, α,α'-diethoxy-o-xylene, α,α'-diethoxy-m-xylene,α,α'-diethoxy-p-xylene, α,α'-diisopropoxy-o-xylene,α,α'-diisopropoxy-m-xylene, α,α'-diisopropoxy-p-xylene,α,α'-di-n-propoxy-p-xylene, α,α'-di-n-butoxy-m-xylene,α,α'-di-n-butoxy-p-xylene, α,α'-di-sec-butoxy-p-xylene,α,α'l-diisobutoxy-p-xylene, 4,4'-dihydroxymethyldiphenyl ether,4,4'-dihydroxymethyldiphenyl, 2,6-dihydroxymethylnaphthalene,4,4'-diacetoxymethyldiphenyl ether, 4,4'-diacetoxymethyldiphenyl,2,6-diacetoxymethylnaphthalene, 4,4'-methoxymethyldiphenyl ether,4,4'-methoxymethyldiphenyl, 4,4'-diethoxymethyldiphenyl ether,4,4'-diisopropoxymethyldiphenyl, 4,4'-diisobutoxymethyldiphenyl ether,α,α'-dimethoxy-2-methyl-p-xylene, α,α'-dimethoxy-3-methyl-m-xylene,α,α'-dihydroxy-2,5-dimethyl-p-xylene,α,α'-dimethoxy-2,5-dimethyl-p-xylene,α,α'-dimethoxy-2,4-dimethyl-1,3-xylene,α,α'-dimethoxy-2,4-dimethyl-1,5-xylene, etc. Among these,α,α'-dimethoxy-p-xylene is preferred.

In the aromatic amine compound represented by the general formula (b),R¹ represents a halogen atom or a hydroxyl, C₁₋₄ alkoxy or C₁₋₅ alkylgroup. The aromatic amine compound may contain 0-3 R¹groups. When 2-3 R¹groups are present, the groups may be either the same or different. Twoof the R¹ groups may join together to form a 5-membered or 6-memberedalicyclic group which may contain one or more side chains. The aromaticamine compound (b) may contain one or two amino groups. Exemplaryaromatic amine compound, suitable for use in the processof the inventioninclude aniline, o-toluidine, m-toluidine,o-ethylaniline,m-ethylaniline, p-ethylaniline, o-isopropylaniline,m-isopropylaniline, p-isopropylaniline, o-n-propylaniline,o-tert-butylaniline, p-tert-butylaniline, o-n-butylaniline,p-sec-butylaniline, 2,3-xylidine, 2,4-xylidine, 2,6-xylidine,3,4-xylidine, 3,5-xylidine, 2-methyl-3-ethylaniline,2-methyl-4-isopropylaniline, 2,6-diethylaniline,2-ethyl-5-tert-butylaniline, 2,4-diisopropylaniline,2,4,6-trimethylaniline, 4-chloroaniline, 4-bromoaniline,4-fluoroaniline, 3-chloroaniline, 3-bromoaniline, 3,4-dichloroaniline,3-chloro-o-toluidine, 3-chloro-p-toluidine,2,6-dimethyl-4-chloroaniline, o-aminophenol, m-aminophenol,p-aminophenol, 2-amino-4-cresol, 4-amino-2-tert-butylphenol,2,6-dimethyl-4aminophenol, 2,6-dichloro-4-aminophenol,2-amino-1,3resorcin, 4-amino-1,3-resorcin, 2-aminohydroquinone,2-methoxyaniline, 3-methoxyaniline,4-methoxyaniline,2-isopropoxyaniline, 2,4-dimethoxyaniline,o-phenylenediamine, m-phenylenediamine, p-phenylenediamine,2,4-diaminotoluene, 2,6-diaminotoluene, 2,4-diaminoethylbenzene,2,6-diaminoethylbenzene, 2,4-diaminoisopropylbenzene,2,4-diamino-tert-butylbenzene, 2,6-diamino-tert-butylbenzene,2,4-diamino-1,3dimethylbenzene, 1,1-dimethyl-4-aminoindane,1,1-dimethyl-4,6-diaminoindane, etc. Preferably toluidines, xylidines,aminophenols and diamines, are employed.Most preferably, aniline isemployed.

As the acid catalyst, it is preferred to use either singly or incombination an inorganic or organic acid, particularly a mineral acid,e.g., hydrochloric acid, phosphoric acid, sulfuric acid or nitric acid,a Friedel-Crafts catalyst such as zinc chloride, stannic chloride,aluminum chloride or ferric chloride, an organic sulfonic acid such asmethanesulfonic acid or p-toluenesulfonic acid, or a super strong acidsuch as trifluoromethanesulfonic acid or "Nafion H" (trade name; productof E.I. du Pont de Nemours & Co., Inc.). Use of a solid acid catalystsuchas an activated clay or zeolite, or a heteropolyacid is alsosuitable for use in the present process. In an industrial applicationhydrochloric acidis preferred due to its economical price. The acidcatalyst may be used in an amount of from about 10 mole % or more,preferably from about 20-100 mole % based on the aromatic aminecompound. Use of the catalyst in an amount less than 10 mole % resultsin a slow reaction velocity and thus makes it difficult to achievecomplete conversion into primary amine compounds. Amounts greater than100 mole % do not give adverse effects to the reaction but are noteconomical.

The reaction temperature is preferably 130° C. or higher. The reactionbecomes extremely slow if the temperature is lower than 130.C. Atemperature range of about 170°-240° C. is preferred in order to shortenthe reaction temperature as much as possible. The reaction time mayrange from 10 hours to 40 hours. As a resin of the formula (a) havinggreater n groups is produced, the reaction time becomesshorter.

An inert solvent may be used in the reaction of the first productionprocess according to this invention. However, the reaction is preferablycarried out without a solvent. After completion of the reaction, theacid employed as a catalyst is neutralized, for example, with a diluteaqueous alkaline solution such as an aqueous solution of caustic soda,an aqueous solution of potassium hydroxide or aqueous ammonia and isthen separated.

When unreacted aromatic amine compound remains in the above reaction, itisdistilled out in vacuum or by steam distillation.

The second process of this invention for the production of the aromaticamine resin will next be described.

According to the second process of this invention, the aromatic aminecompound represented by the general formula (b) and thebishalogenomethyl derivative represented by the general formula (d) canbe reacted in two stages in the absence of a catalyst. In this case, aresin containing a secondary amine is formed in the first stage of thereaction. It is however only necessary to convert the secondary amineinto a primary amineresin by a rearrangement reaction (second-stagereaction). In the rearrangement reaction hydrogen halide, which isproduced upon formation of the primary amine resin, is used as acatalyst. However, in order to accelerate this rearrangement reaction,the reaction is conducted in the same manner as in the first productionprocess of this invention, for example, (a) by increasing the amount ofa catalyst of the same or different kind, (b) by increasing the reactiontemperature or (c) by prolonging the reaction time, compared to thereaction conditions under which a secondary amine resin is formed. It isparticularly effective to increase the amount of the catalyst.

Like the first production process, the second production process of thisinvention has also made it possible to freely produce aromatic amineresins, which range in properties from a low molecular resin composedprincipally of the aromatic amine compound of the general formula (a) inwhich n is 0, to a high molecular weight resin composed principally ofthearomatic amine compound of the general formula (a) in which n isabout 300.The resins obtaine by changing the molar ratio of the aromaticamine compound to the bishalogenomethyl derivative upon conducting thecondensation reaction. Thus, it is possible to produce aromatic amineresins in various forms ranging from those in a liquid form at roomtemperature to those having a high softening point and resinousappearancein accordance with the intended end use. Specifically,aromatic amine resins ranging from liquid resins to low softening pointresins can be obtained when the molar ratio of the aromatic aminecompound to the bishalogenomethyl derivative is increased in thecondensation reaction. Onthe other hand, aromatic amine resins having ahigh softening point can be obtained when the molar ratio of thebishalogenomethyl derivative to the aromatic amine is about thestoichiometric ratio in the condensation reaction.

The molecular weight range and softening point range of the aromaticamine resins obtained in accordance with the second process of thisinvention are similar to those of the resins obtained in accordance withthe first production process.

The aromatic amine compound represented by the general formula (b) ispreferably added in an amount of from about 1-15 moles, preferably fromabout 1.1-10 moles per mole of the bishalogenomethyl derivativerepresented by the general formula (d). The compounds are heated. Asuitable acid catalyst may be added in advance or in the course of thereaction in order to accelerate the reaction.

In the bishalogenomethyl derivative represented by the general formula(d),A is a phenylene group, an alkyl-substituted phenylene group, adiphenylenegroup, a diphenyl ether group, a naphthylenyl group or thelike, and X is achlorine, bromine, fluorine or iodine atom. Exemplarybishalogenomethyl derivatives useful in the practice of this inventioninclude α,α'-dichloro-o-xylene, α,a'-dichloro-m-xylene, α,α'l-dichloro-p-xylene, α,α'-dibromo-o-xylene, α,α'-dibromo-m-xylene,α,α'-dibromo-p-xylene, α,α'-difluoro-o-xylene, α,α'-difluoro-m-xylene,α,α'-difluoro-p-xylene, α,α'-diiodo-o-xylene, α,α'-diiodo-m-xylene,α,α'-diiodo-p-xylene, 4,4'-bis(chloromethyl)diphenyl ether,4,4'-bis(chloromethyl)diphenyl, 2,6-bis(chloromethyl)naphthalene,4,4'-bis(bromoethyl)diphenyl ether, 4,4'bis(bromomethyl)diphenyl,2,6-bis(bromomethyl)naphthalene, 4,4'-bis(fluoromethyl)diphenyl ether,4,4'-bis(fluoromethyl)diphenyl, 4,4'-bis(iodomethyl)diphenyl ether,4,4'-bis(iodomethyl)diphenyl, α,α'-dichloro-2-methyl-p-xylene,α,α'-dichloro-3-methyl-m-xylene, α,α'-dichloro-2,5-dimethyl-p-xylene,α,α'-dibromo-2,5-dimethyl-p-xylene,α,α'-dichloro-2,4-dimethyl-1,3-xylene,α,α'-dichloro-2,4-dimethyl-1,5-xylene. Among these,α,α'-dichloro-p-xylene is preferred.

As R¹ in the aromatic amine compound of the general formula (b) employedin this invention, a similar atom or group as is in the first productionprocess may be chosen as desired depending on the kind of the targetaromatic amine. One or two amino groups are also contained therein.Itsspecific examples and the most preferable compound among such specificexamples are hence as described above.

In the second production process of this invention, an acid catalyst mayalso be used to accelerate the reaction as mentioned above. As the acidcatalyst, any one of acid catalysts usable in the first productionprocesscan be used. Industrially preferred is hydrochloric acid for itseconomicalprice. To the hydrogen halide which is formed in the course ofthe reaction, the catalyst may be added in an amount of from about 100mole % or less based on the aromatic amine compound. Although noproblems would arise even if the catalyst is added beyond that level,use of the catalystin such an excess amount is not economical.

The reaction temperature may range from about 0° C. to about 240° C.during the reaction. However, it is preferred that the temperature befrom about 0°-130° C., more preferably, 20°-100° C. in the first stageof the reaction and from about 130°-240° C. in the second-stagereaction. In order toshorten the reaction time of the second stage asmuch as possible, a temperature range of from about 170°-240° C. isdesirable. The reaction time may be from about 1-10 hours in the firststage and fromabout 5-40 hours in the second stage. The reaction timealso becomes shorter as a resin having greater n in the general formula(a) is produced.

An inert solvent may also be used in the reaction of the secondproduction process according to this invention. However, the reaction isusually carried out without solvent. After completion of the reaction,the acid formed in the reaction or the acid employed as a catalyst isneutralized, for example, with a dilute aqueous alkaline solution suchas an aqueous solution of caustic soda, an aqueous solution of potassiumhydroxide or aqueous ammonia and is then separated.

When unreacted aromatic amine compound remains in the above reaction, itisdistilled out in vacuum or by steam distillation.

The aromatic amine resin of this invention can be obtained in theabove-described manner. Since the bishalogenomethyl derivativerepresentedby the general formula (d) is used as a raw material, acatalyst is not absolutely required for the reaction, and thus aromaticamine resin can beproduced at a more economical price, and the processproduces fewer side reactions.

Thermosetting resin compositions according to this invention will nextbe described.

N,N'-4,4'-diphenylmethanebismaleimide represented by the formula (e) canbeprepared with ease by subjecting 4,4'-diaminodiphenylmethane andmaleic anhydride to a condensation/dehydration reaction by a methodknown per se in the art.

A thermosetting resin composition is then obtained fromN,N'-4,4'-diphenylmethanebismaleimide represented by the formula (e) andthe aromatic amine resin composed of a mixture of aromatic aminecompoundsrepresented by the formula (a). The following methods can beused to produce the thermosetting resin composition.

(1) The bismaleimide and aromatic amine resin can be ground and mixed insolid-solid forms or in solidliquid forms. As an alternative, the resinscan be heat-treated into a prepolymer, followed by grinding into pelletsor powder. It is preferable to choose such heating conditions that theresultant mixture is partially cured to the stage of the prepolymer. Itisgenerally suitable to heat them at from about 70°-220° C. forfromabout 5-240 minutes, preferably at from about 80°-200° C. for from about10-180 minutes.

(2) The bismaleimide and aromatic amine resin can be dissolved in anorganic solvent. The resultant solution is charged into a bad solvent.Crystals thus precipitated are collected by filtration and then driedintopellets or powder. As an alternative, after dissolution in anorganic solvent, the resins can be partially cured to the stage of aprepolymer bya heat treatment. The prepolymer is then charged into a badsolvent. Crystals thus precipitated are collected by filtration and thendried intopellets or powder. Conditions for the heat treatment shouldfollow those employed in the method (1).

Suitable organic solvents for use in processes (1) and (2) above includehalogenated hydrocarbons such as methylene chloride, dichloroethane andtrichloroethylene, ketones such as acetone, methyl ethyl ketone,cyclohexanone and diisopropyl ketone, ethers such as tetrahydrofuran,dioxane and methylcellosolve, aromatic compounds such as benzene,toluene and chlorobenzene, and aprotic polar solvents such asacetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide,dimethylsulfoxide, N-methyl-2-pyrrolidone and1,3-dimethyl-2-imidazolidinone.

It is preferred that the aromatic amine resin composed of the mixture ofthe aromatic amine compounds represented by the formula (a) be used inan amount of from about 5-100 parts by weight, more preferably, fromabout 10-80 parts by weight per 100 parts by weight ofN,N'-4,4'-diphenylmethanebismaleimide represented by the formula (e).

If the amount of the aromatic amine resin is smaller than 5 parts byweight, cured products obtained from the resultant composition may beextremely brittle and may not provide any satisfactory flexuralstrength. If the aromatic amine resin is used in an amount greater than100 parts byweight the resultant cured products may have poor heatresistance.

The following components may be added to the thermosetting resincompositions of this invention as needed to such an extent that theobjects of this invention are not impaired.

(a) Curing accelerators, for example, radical polymerization initiatorssuch as azo compounds and organic peroxides, and ionic catalysts such astertiary amines, quaternary ammonium salts, imidazoles, borontrifluoride and amine salts.

(b) Powdery reinforcing materials and fillers, for example, metal oxidessuch as aluminum oxide and magnesium oxide, metal hydroxides such asaluminum hydroxide, metal carbonates such as calcium carbonate andmagnesium carbonate, diatomaceous earth, basic magnesium silicate,calcined clay, fine particulate silica, molten silica, crystallinesilica,carbon black, kaolin, fine particulate mica, silica flour,graphite, asbestos, molybdenum disulfide, and antimony trioxide. Inaddition, fibrous reinforcing materials and fillers, for example,inorganic fibers such as glass fibers, rock wool, ceramic fibers,alumina fibers and potassium titanate fibers, and organic fibers such ascarbon fibers and aromatic polyamide fibers may also be added.

(c) One or more synthetic resins may also be blended to improve theproperties of the resin composition in end products such as coatingfilms,bonding layers and resin moldings. Such synthetic resins mayinclude thermosetting resins such as phenol resins, epoxy resins,melamine resins and silicone resins, polyamides, polycarbonates,polysulfones, polyether sulfones, polyether ether ketones, modifiedpolyphenylene oxides, polyphenylene sulfides, polyether imides, andfluoroplastics.

The thermosetting resin compositions of this invention can be molded orotherwise formed for practical applications by known molding or formingmethods such as compression molding, transfer molding, extrusion andinjection molding.

This invention will hereinafter be described in more detail by thefollowing Examples, which are intended to be purely exemplary of theinvention. Example 1:

A reaction vessel fitted with a stirrer, a thermometer and aDean-Stark's azeotropic distillation trap was charged with 111.6 g (1.2moles) of aniline as an aromatic amine compound represented by thegeneral formula (b), 66.5 g (0.4 mole) of α,α'-dimethoxy-p-xylene as anaralkyl alcohol derivative represented by the general formula (c) and62.6g (0.6 mole) of a 35% aqueous solution of hydrochloric acid as acatalyst. The contents were heated while feeding nitrogen gas. Waterwhich began to be distilled out into the trap from an internaltemperature of about 1100° C. was taken out of the system. When theinternal temperaturewas raised further, distillation of methanol wasobserved from about 130° C. While distilling out methanol thus formed,the internal temperature was continuously raised. After reaching 170°C., the reaction mixture was maintained at the same temperature for 3hours. Formation of methanol ceased substantially. The reaction mixturewas thereafter heated further to 190°-200° C., at which the reaction wasallowed to proceed for 12 hours. The reaction system was thencooled tolower the internal temperature to 95° C. To the thus-cooled reactionmixture, 168 g of a 15% aqueous solution of caustic soda was added andthen stirred to neutralize the reaction mixture. After allowing theresultant mixture to stand, a water layer appeared as a lowerlayer wasseparated out. Saturated saline (300 g) was added to an upper layer towash the same. The saline was then separated out. The resultant solutionwas heated and dried under a nitrogen gas stream and then filtered underpressure to remove inorganic salts and the like. The filtrate wasconcentrated in a vacuum of 2-3 mmHg to recover 51.9 g of unreactedaniline. The residue was taken out, thereby obtaining 94.5 g of anaromatic amine resin of a pale yellowish brown color.

The composition of the thus-obtained aromatic amine resin according tothisinvention was analyzed by high-performance liquid chromatography. Asa result, it was found to have the following composition:

    ______________________________________                                        Amine compound(s) of                                                          general formula (a)                                                                        n = 0   n = 1   n = 2 n = 3 n ≧ 4                         ______________________________________                                        Mole %       28      16.8    10.5  7.8   36.9                                 ______________________________________                                    

Further, the amine equivalent of the resin as measured by the perchloricacid-glacial acetic acid method was 0.578 equivalent/100 g. Itssoftening point as measured by a ring and ball softening point measuringinstrument according to JIS (Japanese Industrial Standard) K-2548 was68° C. In addition, its average molecular weight was 960.

Results of an IR analysis of the resin are sown in FIG. 1.

EXAMPLE 2

A reaction was conducted in the same manner as in Example 1 except forthe use of 244.4 g (2.0 moles) of 2,4-diaminotoluene as an aromaticamine compound represented by the general formula (b) and 209 g (2.0moles) of 35% hydrochloric acid as a catalyst, whereby 132 g of anaromatic amine resin was obtained as a reddish brown oil.

The composition of the thus-obtained aromatic amine resin according tothisinvention was analyzed by high-performance liquid chromatography. Asa result, it was found to have the following composition:

    ______________________________________                                        Amine compound(s) of                                                          general formula (a)                                                                         n = 0   n = 1     n = 2 n ≧ 3                            ______________________________________                                        Mole %        44.5    29.7      14.6  11.2                                    ______________________________________                                    

The amine equivalent of the resin was 1.204. Its softening point andaverage molecular weight were 46° C. and 550 respectively.

EXAMPLE 3

A reaction was conducted in the same manner as in Example 1 except forthe use of 121.1 g (1.3 moles) of aniline as an aromatic amine compoundrepresented by the general formula (b), 138.28 g (1.0 mole) ofα,α'-dihydroxy-m-xylene as an aralkyl alcohol derivative represented bythe general formula (c) and 33 g (0.325 mole) of concentrated sulfuricacid as a catalyst, whereby 151 g of an aromatic amine resin of a paleyellowish brown color was obtained.

The amine equivalent of the thus-obtained aromatic amine resin was0.496. Its softening point as measured by the ring and ball softeningpoint measuring instrument according to JIS (Japanese IndustrialStandard) K-2548 was 118° C. Its average molecular weight was 6500.

EXAMPLE 4

A reaction vessel was charged with 109 g (1.0 mole) of p-aminophenol asan aromatic amine compound represented by the general formula (b), 110.2g (0.5 mole) of α,α'-diacetoxy-p-xylene as an aralkyl alcohol derivativerepresented by the general formula (c), and 6.8 g (0.05 mole) of zincchloride and 19 g (0.1 mole) of p-toluene sulfonic acid as catalysts.They were reacted under reduced pressure by means of a water jet pump.The reaction started from about 130° C. and the internal temperaturearose to 170° C. in 3 hours. Acetic acid generated in the course of thereaction was recovered in a deep-cooling trap. After maintaining thereaction mixture at the same temperature for 3 hours, thereactiontemperature was raised further to 200° C., followed by aging at200°-210° C. for 1 hour before completion of the reaction. The reactionmixture was cooled down to 95° C., at which 300 m of toluene was addedto dissolve the reaction mixture under stirring. After adding 20.2 g oftriethylamine to the resultant mixture, 200 ml of water was added. Thethus-prepared mixture was stirred and then allowed to stand. A waterlayer that occurred as a lower layer was separated out. An upper layerwas washed once again with 200 ml of water and the water was thereafterseparated out. The resulting solution was concentrated in a vacuum toremove toluene and unreacted p-aminophenol. Asa brown resin, 138 g of anaromatic amine resin was obtained.

The amine equivalent of the thus-obtained aromatic amine resin was0.525. Its softening point as measured by the ring and ball softeningpoint measuring instrument according to JIS (Japanese IndustrialStandard) K-2548 was 94° C. Its average molecular weight was 2200.

EXAMPLE 5

A reaction was conducted in the same manner as in Example 1 except forthe use of 745 (8.0 moles) of aniline, 664 g (4.0 moles) ofα,α'-dimethoxy-p-xylene and 420 g (4.0 moles) of a 35% aqueoussolutionof hydrochloric acid as a catalyst, whereby 747 g of an aromatic amineresin of a pale yellowish brown color was obtained.

The composition of the thus-obtained aromatic amine resin according tothisinvention was analyzed by high-performance liquid chromatography. Asa result, it was found to have the following composition:

    ______________________________________                                        Amine compound(s) of                                                          general formula (a)                                                                         n = 0   n = 1     n = 2 n ≧ 3                            ______________________________________                                        Mole %        17.0    14.5      13.2  55.2                                    ______________________________________                                    

The amine equivalent of the resin was 0.520 equivalent/100 g. Itssofteningpoint and average molecular weight were 61° C. and 2100respectively.

EXAMPLES 6-14

Various aromatic amine resins of this invention as shown in Table 1 wereobtained by separately conducting reactions in the same manner as inExample 1 except that the kind of the aromatic amine compoundrepresented by the general formula (b), the kind and amount of thearalkyl alcohol derivative represented by the general formula (c) andthe kind and amount of the catalyst and the reaction conditions wereselected as shown in Table 1.

    TABLE 1      Syntheses of Various Aromatic Amine Resins  Aralkyl alcohol  Reaction     Aromatic amine derivatives Catalyst conditions Synthesized resin     Amount  Amount  Amount Temp./time  Yield  S.P.* Ex. Kind (mole) Kind     (mole) Kind (mole) (°C.) (hr) Structural unit (g) M.W. (°C.     )                   6 o-Toluidine 1.2 4,4'-Dihydroxy-methyldiphenylether 0.12     HCl 0.4 140-170/5170-195/12      ##STR8##      50.5  580 Oily      7 2,4-Xylidine 1.2 α,α'-Diiso-propoxy-p-xylene 0.4 " 0.6     130-170/5170-200/8      ##STR9##      116 1350 75      8 2,4,6-Tri-methyl-aniline 1.2 α,α'-Dihydroxy-2,5-dimethyl-p     -xylene 0.3 " 0.24 130-170/5200-210/8      ##STR10##      92  850 70      9 p-n-Propyl-aniline 1.2 α,α'-Dimethoxy-p-xylene 1.0 " 0.6     130-150/5180-200/14      ##STR11##      246 12000  142                                                          p      10 m-Isopropoxy-aniline 1.2 α,α'-Dimethoxy--xylene 0.4 "     0.24 130-150/3170-190/6      ##STR12##      120 1200 56      11 p-Chloro-aniline 1.2 α,α'-Dimethoxy-P-xylene 0.4 H.sub.3     PO.sub.4 0.24 150-170/3190-200/8      ##STR13##      118 1150 78      12 4-Chloro-o-toluidine 1.2 α,α'-Dimethoxy-P-xylene 0.4 HCl     0.6 150-170/5190-200/12      ##STR14##      120 1100 75      13 3,5-Dichloro-4-aminophenol 1.2 α,α'-Dimethoxy-P-xylene     0.4 " 0.6 150-170/5170-190/12      ##STR15##      135 1250 75                                                             P      14 5-tert-Butyl-o-toluidine 1.2 α,α'-Dimethoxy--xylene 0.4     CF.sub.3 SO.sub.3      H 0.15 130-150/3170-190/6     ##STR16##      142 1520 87    *Softening point as measured by the ring and ball softening point measurin    apparatus according to JIS (Japanese Industrial Standard) K2548.

EXAMPLE 15

In 1400 g of dry o-dichlorobenzene, 100 g of the aromatic amine resinobtained in Example 1 was dissolved. Thereafter, 253 g of phosgene wasblown at 5°-10° C. into the solution over 3 hours. While slowly blowingphosgene into the solution, the solution was heated and aged at120°-140° C. for 2 hours. The feeding of phosgene was then stopped andswitched over to the feeding of nitrogen gas. The reaction system wasthoroughly purged with nitrogen gas and was then cooled. The reactionmixture was concentrated in a vacuum to recover o-dichlorobenzene as thesolvent, so that 111 g of an isocyanated resin were obtained in the formof a pale brown oil.

In 400 g of methylene chloride, 10.4 g of the isocyanated resin obtainedasdescribed above was dissolved to provide "Solution A". "Solution B",which consisted of 2.2 g of "EDTDA" (product of Ethyl Corporation), 10 gof "JEFFAMINE T-5000" (trade name; product of Texaco Chemical Company)and 2500 g of methylene chloride, was then mixed with the abovementioned"Solution A". The resultant mixture was cast on a glass plate. It wasallowed to stand overnight, followed by post curing at 120° C. for 2hours. A good polyurea film was successfully obtained.

EXAMPLE 16

Forty (40) parts by weight of the aromatic amine obtained in Example 1weremixed with 100 parts by weight of "Bismaleimide-s" (trade name;product of Daiwa Kasei Co., Ltd.). The resultant mixture was heated andcured at 180° C. for 10 minutes to prepare a prepolymer.

The solubility of the prepolymer in various solvents was measured.Results are summarized under Experiment 1 in Table 2. In addition, theexternal appearance, softening point, gelling time and bulk specificgravity of theprepolymer are summarized under Experiment 1 in Table 3.For the sake of comparison, commercial "Kerimid-1050" (trade name;molding grade; product of Nippon Polyimide Co., Ltd.) was also testedsimilarly. Results are shown under Comparative Experiment 1 in Table 2and Table 3 respectively.

Next, the prepolymer and "Kerimid-1050" were separately subjected tocompression molding at 200° C. under 40 kg/cm² for 1 hour. Theresultantmoldings were thereafter post-cured at 250° C. for 4 hours, therebyproducing test pieces of cured resins. Mechanical strengthsand thermalproperties of the test pieces were measured. Results are shownrespectively under Experiment 1 and Comparative Experiment 1 in Table 3.

                  TABLE 2                                                         ______________________________________                                        Solubility of Heat-Cured Prepolymer (wt. %)                                   Measured at 25° C.                                                                      Experiment 1                                                                  Aromatic amine                                                                            Comparative                                                       resin/bismale-                                                                            Experiment 1                                     Solvent          imide-s     Kerimid-1050                                     ______________________________________                                        N-Methylpyrrolidone                                                                            >50         >50                                              N,N-Dimethylacetamide                                                                          >50         >50                                              N,N-Dimethylformamide                                                                          >50         48                                               1,4-Dioxane      35          <1                                               Diethylene glycol                                                                              <1          <1                                               dimethyl ether                                                                m-Cresol         38          34                                               Methylene chloride                                                                             28          <1                                               Trichloroethylene                                                                              <1          <1                                               Benzene          <1          <1                                               Toluene          <1          <1                                               Methoxybenzene   <1          <1                                               Acetone          <1          <1                                               Methyl ethyl ketone                                                                            <1          <1                                               ______________________________________                                    

                                      TABLE 3                                     __________________________________________________________________________    Basic Physical Properties                                                                                      Experiment 1                                                                  Aromatic amine                                                                        Comparative                                                           resin/bismale-                                                                        Experiment 1                         Tested property Testing method                                                                           Unit  imide-s Kerimid-1050                         __________________________________________________________________________    Prepolymer                                                                    External appearance                                                                             --       --    Yellow powder                                                                         Yellow powder                        Softening point Capillary method                                                                         °C.                                                                          105     107                                  Gelling time    200° C. hot plate                                                                 sec   62-73   56-68                                                method                                                        Bulk specific gravity                                                                         JIS K-6911 g/cc  0.44    0.42                                 Molding                                                                       post-cured at 250° C. for 4 hours)                                     Specific gravity                                                                              JIS K-6911 --    1.30    1.31                                 Flexural strength                                                                             JIS K-6711, 25° C.                                                                kg/mm.sup.2                                                                         12.8    8.6                                  Flexural modulus                                                                              JIS K-6911, 25° C.                                                                kg/mm.sup.2                                                                         372     352                                  Izod impact strength                                                                          JIS K-6911,                                                                              kg · cm/cm                                                                 18      13                                                   un-notched                                                    Barcol hardness ASTM D 2583                                                                              --    45      47                                   Heat distortion temp.                                                                         JIS K-6911, 18.5/cm.sup.2                                                                °C.                                                                          >260    >260                                 Pyrolysis starting                                                                            TGA method, heating                                                                      °C.                                                                          341     322                                  temperature     rate: 10° C./min                                       Glass transition                                                                              TMA penetration                                                                          °C.                                                                          >300    >300                                 temperature     method                                                        Expansion coefficient                                                                         JIS K-6911 cm/cm/° C.                                                                   5.69 × 10.sup.-5                                                                5.89 × 10.sup.-5               Water absorption rate                                                                         25° C./24 hrs,                                                                    %     0.48    0.91                                                 immersed in water                                             __________________________________________________________________________

EXAMPLE 17

A reaction vessel fitted with a stirrer and a thermometer was chargedwith 111.6 g (1.2 moles) of aniline as an aromatic amine compoundrepresented by the general formula (b) and 70.0 g (0.4 mole) ofα,α'-dichloro-p-xylene as a bishalogenomethyl derivative represented bythe general formula (d). The contents were heated while feeding nitrogengas. Although evolution of heat was observed from an internaltemperature of about 30° C., the contents were continuously heated andmaintained at 85°-100° C. for 3 hours (first-stage reaction). They werethereafter heated and reacted at 190°-200° C. for 20 hours (second-stagereaction). The reaction system was then cooled to lower the internaltemperature to 95° C. To the thus-cooled reaction mixture, 230 g of a15% aqueous solution of caustic soda was added. They were stirred toneutralize the reaction mixture. After allowing the resultant mixture tostand, a water layer appeared as a lower layer was separated out.Saturated saline (300 g) was added to an upper layer so as to wash thesame. The resultant solution was heated and dried under a nitrogen gasstream and was then filtered under pressure to remove inorganic saltsand the like. The filtrate was concentrated in a vacuum of 2-3 mmHg torecover 48.5 g of unreacted aniline. The residue was taken out, therebyobtaining 100 g of an aromatic amine resin of a pale yellowish browncolor.

The composition of the aromatic amine resin obtained by the secondprocess of this invention as described above was analyzed byhigh-performance liquid chromatography. As a result, it was found tohave the following composition:

    ______________________________________                                        Amine compound(s) of                                                          general formula (a)                                                                        n = 0   n = 1   n = 2 n = 3 n ≧ 4                         ______________________________________                                        Mole %       27.8    19.2    14.0  11.8  27.2                                 ______________________________________                                    

Further, the amine equivalent of the resin as measured by the perchloricacid-glacial acetic acid method was 0.65 equivalent/100 g. Its softeningpoint as measured by a ring and ball softening point measuringinstrument according to JIS (Japanese Industrial Standard) K-2548 was64° C. In addition, its average molecular weight was 880.

EXAMPLE 18

The procedure of Example 17 was repeated except that 61.1 g (0.5 mole)of 2,4-diaminotoluene and 29.2 g (0.1 mole) ofα,α'-dibromo-2,5-dimethyl-p-xylene were used as an aromatic aminecompound represented by the general formula (b) and a bishalogenomethylderivative represented by the general formula (d) respectively and thereaction time of the second stage was changed to 30 hours, whereby 32.5g of an aromatic amine resin was obtained.

The composition of the aromatic amine resin thus obtained by the secondprocess of this invention as described above was analyzed byhigh-performance liquid chromatography. As a result, it was found tohave the following composition:

    ______________________________________                                        Amine compound(s) of                                                          general formula (a)                                                                         n = 0   n = 1     n = 2 n ≧ 3                            ______________________________________                                        Mole %        41.8    21.2      13.1  23.9                                    ______________________________________                                    

The amine equivalent of the resin was 1.212. Its softening point andaverage molecular weight were 46° C. and 520 respectively.

EXAMPLE 19

The procedure of Example 17 was repeated except for the use of 53.6 g(0.5 mole) of mixed toluidine, which consisted of 19% of the o-isomer,53% of the m-isomer and 28% of the p-isomer, and 106.9 g (0.4 mole) of4,4'-bis(chloromethyl)diphenyl ether as an aromatic amine compoundrepresented by the general formula (b) and a bishalogenomethylderivative represented by the general formula (d) respectively, whereby116 g of an aromatic amine resin was obtained.

The amine equivalent of the aromatic amine resin obtained by the secondprocess of this invention as described above was 0.35. Its softeningpointas measured by the ring and ball softening point measuringinstrument according to JIS (Japanese Industrial Standard) K-2548 was136° C. Its average molecular weight was 13200.

EXAMPLE 20

A reaction vessel similar to that employed in Example 17 was chargedwith 93.1 g (1 mole) of aniline as an aromatic amine compoundrepresented by the general formula (b) and 17.5 g (0.1 mole) ofa,al-dichloro-m-xylene asa bishalogenomethyl derivative represented bythe general formula (d). The contents were heated while feeding nitrogengas. Although evolution of heat was observed from an internaltemperature of about 30° C., thecontents were continuously heated andmaintained at 70°-80° C. for 5 hours (first-stage reaction). Next, 31.3g (0.3 mole) of a 35% aqueous solution of hydrochloric acid was chargedinto the reaction mixture, and the resultant mixture was heated as was.Water formed in the course of the heating was distilled out of thesystem. They were thereafter reacted at 180°-190° C. for 16 hours(second-stage reaction). Cooling, stirring and neutralization,separation and removal, washing and separation, heating and drying,pressure filtration and vacuum concentration were then carried out as inExample 17, thereby obtaining 25 g of an aromatic amine resin as a palebrown oil.

The composition of the aromatic amine resin obtained by the secondprocess of this invention as described above was analyzed byhigh-performance liquid chromatography. As a result, it was found tohave the following composition:

    ______________________________________                                        Amine compound(s) of                                                          general formula (a)                                                                         n = 0   n = 1     n = 2 n = 3                                   ______________________________________                                        Mole %        79.0    17.7      2.7   0.6                                     ______________________________________                                    

Further, the amine equivalent of the resin was 0.674, and its averagemolecular weight was 330.

EXAMPLE 21

The procedure of Example 20 was repeated except for the use of 17.5 g(0.1 mole) of α,α'-dichloro-p-xylene as a bishalogenomethyl derivativerepresented by the general formula (d) and the use of 19.0 g (0.1 mole)of p-toluenesulfonic acid as a reaction accelerator before thesecond-stage reaction, thereby obtaining 25.8 g of an aromatic amineresinas a pale brown oil.

The amine equivalent of the aromatic amine resin obtained by the secondprocess of this invention adescribed above was 0.671. Its compositionwas substantially the same as the resin obtained in Example 20.

EXAMPLES 22-25

A stainless reaction vessel fitted with a stirrer, a reflux condenserand anitrogen inlet tube was charged withN,N'-4,4'-diphenylmethanebismaleimide and the aromatic amine resin,which was obtained in Example 1, in amounts given respectively in termsof parts by weight in Table 4. The contents were heated and cured at180° C. for 20 minutes, followed by defoaming ing at 150° C. underreduced pressure (10-15 mmHg) for 30minutes. The melt was then cooleddown to room temperature. In the above-described manner, resincompositions were separately obtained in a form solidified in a browntransparent glassy state.

While separately heating and melting the compositions, they wereindividually filled in molds heated at 180° C. and were then maintainedunder 50 kg/cm² at 200° C. for 30 minutes to perform compressionmolding. Resultant moldings were taken out of the respectivl molds andthen post-cured for 4 hours in an oven of 250°C., thereby obtaining testpieces of cured resins whose length, width and thickness were 127 mm,12.7 mm and 6.4 mm respectively.

The heat distortion temperatures of those test pieces were measured inaccordance with ASTM D-648 while their bending tests were conducted inaccordance with ASTM D-790. In addition, their pyrolysis startingtemperatures were also measured at a heating rate of 10.C/min in air.Results are summarized in Table 4.

EXAMPLES 26-38 & COMPARATIVE EXAMPLES 1-2

The procedure of Examples 22-25 was repeated using 100 parts by weightof N,N'-4,4'-diphenylmethanebismaleimide and the aromatic amine resins,whichare given in Table 4, in amounts indicated in terms of parts byweight in Table 4. Results are also shown in Table 4.

COMPARATIVE EXAMPLE 3

The procedure of Examples 22-25 was repeated except for the use ofN,N'-4,4'-diphenylmethanebismaleimide and 4,4'-diaminodiphenylmethane intheir respective amounts shown in terms of parts by weight in Table 4.Results are also given in Table 4.

COMPARATIVE EXAMPLE 4

Moldings were produced in the same manner as in Examples 22-25 by using"Kerimid-1050" (trade name for a polyaminobismaleimide resin; product ofJapan Polyimide Co., Ltd.) instead of the resin compositions of thisinvention. various physical properties were measured. Results are alsogiven in Table 4.

The results set forth in Table 4 show that the thermosetting resincompositions of this invention are high in both flexural strength andflexural modulus and also have excellent heat resistance as demonstratedby the heat distortion temperatures all above 290° C. andpyrolysistemperatures all above 340° C.

                                      TABLE 4                                     __________________________________________________________________________    Examples 22-38 & Comparative Examples 1-4                                                      Aromatic amine                                                                         Flexural                                                                            Flexural                                                                            Heat Pyrolysis                          Bismaleimide     resin    strength                                                                            modulus                                                                             distortion                                                                         starting                           (wt. parts)      (wt. parts)                                                                            (kg/mm.sup.2)                                                                       (kg/mm.sup.2)                                                                       (°C.)                                                                       temp. (°C.)                 __________________________________________________________________________    Ex. 22                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                            Ex. 1 (10)                                                                             10.2  351   >300 371                                    methanebismale-                                                               imide                                                                     Ex. 23                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                            Ex. 1 (30)                                                                             12.0  365   >300 369                                    methanebismale-                                                               imide                                                                     Ex. 24                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                            Ex. 1 (50)                                                                             12.8  372   >300 362                                    methanebismale-                                                               imide                                                                     Ex. 25                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                            Ex. 1 (80)                                                                             11.5  370    297 357                                    methanebismale-                                                               imide                                                                     Ex. 26                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                            Ex. 5 (50)                                                                             11.9  389   >300 360                                    methanebismale-                                                               imide                                                                     Ex. 27                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                            Ex. 2 (50)                                                                             11.9  375    294 354                                    methanebismale-                                                               imide                                                                     Ex. 28                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                            Ex. 3 (50)                                                                             12.6  370   >300 361                                    methanebismale-                                                               imide                                                                     Ex. 29                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                            Ex. 4 (50)                                                                             11.3  369   >300 356                                    methanebismale-                                                               imide                                                                     Ex. 30                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                            Ex. 6 (50)                                                                             13.1  389    290 350                                    methanebismale-                                                               imide                                                                     Ex. 31                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                            Ex. 7 (50)                                                                             11.7  387    294 342                                    methanebismale-                                                               imide                                                                     Ex. 32                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                            Ex. 8 (10)                                                                             12.0  375    297 349                                    methanebismale-                                                               imide                                                                     Ex. 33                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                            Ex. 9 (50)                                                                             12.0  380   >300 351                                    methanebismale-                                                               imide                                                                     Ex. 34                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                             Ex. 10 (50)                                                                           12.4  370   >300 350                                    methanebismale-                                                               imide                                                                     Ex. 35                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                             Ex. 11 (50)                                                                           11.9  383   >300 351                                    methanebismale-                                                               imide                                                                     Ex. 36                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                             Ex. 12 (50)                                                                           11.7  383   >300 352                                    methanebismale-                                                               imide                                                                     Ex. 37                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                             Ex. 13 (50)                                                                           12.0  371   >300 353                                    methanebismale-                                                               imide                                                                     Ex. 38                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                             Ex. 14 (50)                                                                           12.2  376   >300 341                                    methanebismale-                                                               imide                                                                     Comp.                                                                             N,N'-4,4'-Diphenyl-                                                                     (100)                                                                                -- (0)                                                                             Molding was infeasible.                                                                        418                                Ex. 1                                                                             methanebismale-       (Cracks were formed.)                                   imide                                                                      Comp.                                                                            N,N'-4,4'-Diphenyl-                                                                     (100)                                                                            Ex. 1 (150)                                                                            8.9   349    280 331                                Ex. 2                                                                             methanebismale-                                                               imide                                                                     Comp.                                                                             N,N'-4,4'-Diphenyl-                                                                     (100)                                                                            4,4'-diamino-                                                                          8.6   352    276 330                                Ex. 3                                                                             methanebismale-                                                                            diphenylmethane                                                  imide        (30)                                                         Comp.                                                                             Kerimid-1050          8.6   352    285 333                                Ex. 4                                                                         __________________________________________________________________________

As has been described above, the aromatic amine resins of this inventionare composed of primary amines and hence facilitate isocyanation,maleimidation and epoxidation. Accordingly, they are also useful as rawmaterials for polyamides and the like.

When the aromatic amine resins of this invention are used as curingagents or raw materials for other resins, the resulting resins haveexcellent mechanical strength, dimensional stability, heat resistance,and stabilityto light and oxygen in air, and their curing speeds arealso high.

The aromatic amine resins of this invention can readily provideprepolymersbecause they are soluble in a solvent of a low melting point.

Since the aromatic amine resins of this invention have such advantageouseffects, they can be used in a wide variety of fields, for example, ascuring agents, raw materials for cured resins, chelate resins,ion-exchange resins, molding materials, insulating paints, bondingagents,rubber modifiers, additives to various resins, deacidificationagents, and raw materials for polyimides, polyamides andpolyamideimides, etc.

Further, the aromatic amine resins of this invention can be producedfrom economical raw materials by a simple operation, and can be obtainedby a process which is practically free of pollution and byproducts. Itis also possible to produce aromatic amine resins in various forms,ranging from those in a liquid form at room temperature to those in aresinous form having a high softening point, in accordance with the enduse. In the second production process of this invention in particular,there are such merits that catalyst is not absolutely required for thereaction, the aromatic amine resins can be produced economically, andless side reactions take place.

In addition, the thermosetting resins according to this invention havesuperb mechanical strength and heat resistance. They are hence expectedtofind wide-spread utility in fields in which high heat resistance isrequired in recent years, for example, the electrical and electronicfield, the mechanical field such as aircrafts and vehicles, and the likefield. They can therefore be used advantageously in the industry.

Other embodiments of the invention will be apparent to those skilled intheart from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with the true scope and spiritof the invention being indicated by the following claims.

We claim:
 1. A thermosetting resin composition comprising about 100parts by weight of N,N'-4,4'-diphenylmethanebismaleimide represented byformula (e): ##STR17## and from about 5 to about 100 parts by weight ofan aromatic amine resin comprising a mixture of aromatic amine compoundsrepresented by the formula (a): ##STR18## wherein A represented aphenylene, alkyl-substituted phenylene, diphenylene, diphenyl ether ornapthylenyl group, R¹ represents a halogen atom, a hydroxyl group, a C₁-C₄ alkoxy or a C₁ -C₅ lkyl group, l is 1 or 2, m is 0, 1, 2 or 3, n isan integer from 0 to 300 and when m is 2 or 3 and said R¹ groups arethes ame or different and two R¹ groups may join to form a 5- or6-membered alicyclic moiety.
 2. The thermosetting resin composition ofclaim 1, wherein l is 1 and m is
 0. 3. The thermosetting resincomposition of claim 2, wherein n is 0, 1, 2, 3 or
 4. 4. Thethermosetting resin composition of claim 3, where A is a phenylenegroup.
 5. The thermosetting resin composition of claim 1, wherein A is aphenylene group.
 6. The thermosetting resin composition of claim 5,wherein l is 1 and m is
 0. 7. The thermosetting resin composition ofclaim 1, wherein m is 2 or 3 and two said R¹ groups join to form a 5- or6-membered alicyclic moiety having at least one side chain.